LMH5401-SP: Recommended amplifier cascade for total gain of ~22 V/V

Jim Brinkhurst1

Part Number: LMH5401-SP
Other Parts Discussed in Thread: ADC12D1620QML-SP, LMH5401

Hi Amplifier experts!

My customer has an application requiring SE to differential conversion and amplification, and driving of the ADC12D1620QML-SP inputs. The signal is coming from an optical receiving circuit with SE output.

The stated gain requirement is ~22 V/V. Can this be achieved with a single SE to Diff LMH5401 stage, or would it be better to use 2 cascaded devices?

If the latter, what is the best gain configuration of each stage?

Finally, what is the recommended space-rated negative supply solution to provide the -1.25V supply required to properly match the output common mode of the amplifier to the input common mode of the ADC12D1620QML-SP?

Thanks in advance!

Best regards,

Jim B

over 5 years ago

0 Michael Steffes over 5 years ago

Guru 48395 points

Well Jim, as you know this question is floating in space without the required BW

0 Jim Brinkhurst1 over 5 years ago in reply to Michael Steffes

TI__Mastermind 44680 points

Hi Michael

Sorry about that! The amplifier is processing a pulse train running at around 125 Mpulses/sec and it will be sampled at 1 Gsample/sec. So the effective bandwidth needs to be approximately 500 MHz.

Best regards,

Jim B

0 Michael Steffes over 5 years ago in reply to Jim Brinkhurst1

Guru 48395 points

Well a single stage at gain of 22 will be about 300MHz BW (depending on source Z)

if you must have 500MHz, perhaps a first stage at gain of 5 followed by a stage at gain of 4.4, your 500Mhz is coming from Nyquist on the 1G ADC, probably need an interstage RLC filter at the ADC to set that.

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LMH5401-SP: Recommended amplifier cascade for total gain of ~22 V/V